.\" $OpenBSD: d2i_PrivateKey.3,v 1.10 2021/10/19 12:03:46 schwarze Exp $
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.Dd $Mdocdate: October 19 2021 $
.Dt D2I_PRIVATEKEY 3
.Os
.Sh NAME
.Nm d2i_PrivateKey ,
.Nm d2i_AutoPrivateKey ,
.Nm d2i_PrivateKey_bio ,
.Nm d2i_PrivateKey_fp ,
.Nm i2d_PrivateKey ,
.Nm i2d_PrivateKey_bio ,
.Nm i2d_PrivateKey_fp ,
.Nm i2d_PKCS8PrivateKeyInfo_bio ,
.Nm i2d_PKCS8PrivateKeyInfo_fp ,
.Nm d2i_PublicKey ,
.Nm i2d_PublicKey
.Nd decode and encode EVP_PKEY objects
.Sh SYNOPSIS
.In openssl/evp.h
.Ft EVP_PKEY *
.Fo d2i_PrivateKey
.Fa "int type"
.Fa "EVP_PKEY **val_out"
.Fa "const unsigned char **des_in"
.Fa "long length"
.Fc
.Ft EVP_PKEY *
.Fo d2i_AutoPrivateKey
.Fa "EVP_PKEY **val_out"
.Fa "const unsigned char **des_in"
.Fa "long length"
.Fc
.Ft EVP_PKEY *
.Fo d2i_PrivateKey_bio
.Fa "BIO *in_bio"
.Fa "EVP_PKEY **val_out"
.Fc
.Ft EVP_PKEY *
.Fo d2i_PrivateKey_fp
.Fa "FILE *in_fp"
.Fa "EVP_PKEY **val_out"
.Fc
.Ft int
.Fo i2d_PrivateKey
.Fa "EVP_PKEY *val_in"
.Fa "unsigned char **des_out"
.Fc
.Ft int
.Fo i2d_PrivateKey_bio
.Fa "BIO *out_bio"
.Fa "EVP_PKEY *val_in"
.Fc
.Ft int
.Fo i2d_PrivateKey_fp
.Fa "FILE *out_fp"
.Fa "EVP_PKEY *val_in"
.Fc
.Ft int
.Fo i2d_PKCS8PrivateKeyInfo_bio
.Fa "BIO *out_bio"
.Fa "EVP_PKEY *val_in"
.Fc
.Ft int
.Fo i2d_PKCS8PrivateKeyInfo_fp
.Fa "FILE *out_fp"
.Fa "EVP_PKEY *val_in"
.Fc
.Ft EVP_PKEY *
.Fo d2i_PublicKey
.Fa "int type"
.Fa "EVP_PKEY **val_out"
.Fa "const unsigned char **des_in"
.Fa "long length"
.Fc
.Ft int
.Fo i2d_PublicKey
.Fa "EVP_PKEY *val_in"
.Fa "unsigned char **des_out"
.Fc
.Sh DESCRIPTION
These are algorithm-independent interfaces to decode and encode
private and public keys.
For details about the semantics, examples, caveats, and bugs, see
.Xr ASN1_item_d2i 3 .
.Pp
.Fn d2i_PrivateKey
decodes a private key using algorithm
.Fa type .
It attempts to use any algorithm specific format or the PKCS#8 unencrypted
.Vt PrivateKeyInfo
format defined in RFC 5208 section 5.
The
.Fa type
parameter should be a public key algorithm constant such as
.Dv EVP_PKEY_RSA .
An error occurs if the decoded key does not match
.Fa type .
.Pp
.Fn d2i_AutoPrivateKey
is similar to
.Fn d2i_PrivateKey
except that it attempts to automatically detect the algorithm.
.Pp
.Fn d2i_PrivateKey_bio
and
.Fn d2i_PrivateKey_fp
are similar to
.Fn d2i_PrivateKey
except that they read from a
.Vt BIO
or
.Vt FILE
pointer.
.Pp
.Fn i2d_PrivateKey
encodes
.Fa val_in .
It uses an algorithm specific format or, if none is defined for
that key type, the PKCS#8 unencrypted
.Vt PrivateKeyInfo
format.
.Pp
.Fn i2d_PrivateKey_bio
and
.Fn i2d_PrivateKey_fp
are similar to
.Fn i2d_PrivateKey
except that they write to a
.Vt BIO
or
.Vt FILE
pointer and use a different convention for their return values.
.Pp
.Fn i2d_PKCS8PrivateKeyInfo_bio
and
.Fn i2d_PKCS8PrivateKeyInfo_fp
encode
.Fa val_in
in PKCS#8 unencrypted
.Vt PrivateKeyInfo
format.
They are similar to
.Fn i2d_PrivateKey
except that they don't use any algorithm-specific formats
and that they write to a
.Vt BIO
or
.Vt FILE
pointer rather than to a buffer.
.Pp
All these functions use DER format and unencrypted keys.
Applications wishing to encrypt or decrypt private keys should use other
functions such as
.Xr d2i_PKCS8PrivateKey_bio 3
instead.
.Pp
If
.Pf * Fa val_out
is not
.Dv NULL
when calling
.Fn d2i_PrivateKey
or
.Fn d2i_AutoPrivateKey
(i.e. an existing structure is being reused) and the key format is
PKCS#8, then
.Pf * Fa val_out
will be freed and replaced on a successful call.
.Pp
.Fn d2i_PublicKey
calls
.Xr d2i_DSAPublicKey 3 ,
.Xr o2i_ECPublicKey 3 ,
or
.Xr d2i_RSAPublicKey 3
depending on
.Fa type
and stores the result in the returned
.Vt EVP_PKEY
object.
.Pp
.Fn i2d_PublicKey
calls
.Xr i2d_DSAPublicKey 3 ,
.Xr i2o_ECPublicKey 3 ,
or
.Xr i2d_RSAPublicKey 3
depending on the algorithm used by
.Fa val_in .
.Sh RETURN VALUES
.Fn d2i_PrivateKey ,
.Fn d2i_AutoPrivateKey ,
.Fn d2i_PrivateKey_bio ,
.Fn d2i_PrivateKey_fp ,
and
.Fn d2i_PublicKey
return a valid
.Vt EVP_PKEY
structure or
.Dv NULL
if an error occurs.
.Pp
.Fn i2d_PrivateKey
and
.Fn i2d_PublicKey
return the number of bytes successfully encoded or a negative value if
an error occurs.
.Pp
.Fn i2d_PrivateKey_bio ,
.Fn i2d_PrivateKey_fp ,
.Fn i2d_PKCS8PrivateKeyInfo_bio ,
and
.Fn i2d_PKCS8PrivateKeyInfo_fp
return 1 for success or 0 if an error occurs.
.Pp
For all functions, the error code can be obtained by calling
.Xr ERR_get_error 3 .
.Sh SEE ALSO
.Xr d2i_PKCS8_PRIV_KEY_INFO 3 ,
.Xr d2i_PKCS8PrivateKey_bio 3 ,
.Xr EVP_PKEY_new 3 ,
.Xr EVP_PKEY_type 3 ,
.Xr PEM_write_PrivateKey 3 ,
.Xr PKCS8_PRIV_KEY_INFO_new 3
.Sh STANDARDS
RFC 5208: Public-Key Cryptography Standards (PKCS) #8: Private-Key
Information Syntax Specification
.Sh HISTORY
.Fn d2i_PrivateKey ,
.Fn i2d_PrivateKey ,
.Fn d2i_PublicKey ,
and
.Fn i2d_PublicKey
first appeared in SSLeay 0.6.0 and have been available since
.Ox 2.4 .
.Pp
.Fn d2i_AutoPrivateKey ,
.Fn d2i_PrivateKey_bio ,
.Fn d2i_PrivateKey_fp ,
.Fn i2d_PrivateKey_bio ,
.Fn i2d_PrivateKey_fp ,
.Fn i2d_PKCS8PrivateKeyInfo_bio ,
and
.Fn i2d_PKCS8PrivateKeyInfo_fp
first appeared in OpenSSL 0.9.5 and have been available since
.Ox 2.7 .
